Effects of cobalt content on mechanical and corrosion properties of electroless Ni‐Co‐P/TiN nanocomposite coatings

Abstract

Ternary Ni‐Co‐P/TiN (20 nm) nanocomposite coatings with Co content in the range of 0–23 wt% were successfully co‐deposited on Al alloys by electroless plating. The morphology, composition, microstructure, micro‐hardness, wear behavior, and corrosion properties of the coatings were tested using SEM, EDS, XRD, Vickers hardness, ball‐on‐disc wear tester, and electrochemical workstation, respectively. The effect of Co content on the tribological and corrosion properties of Ni‐Co‐P/TiN coatings was studied. It is found that all the coatings have a compact and rough granular structure with sub‐micro globules non‐uniformly distributed on the surface. The grain size and the content of Ni and P decrease, but the micro‐hardness, adhesion force, friction coefficient, and corrosion resistance correspondingly enhance with the increase of Co content in Ni‐Co‐P/TiN coatings. The improved corrosion resistance of Ni‐Co‐P/TiN coating is due to the passivation behavior and small grain caused by the introduction of Co. Based on the excellent properties on the wear and corrosion resistance, ternary Ni‐Co23‐P/TiN coating with high Co content, may be applied as an optimum protective coating for Al alloys.

The effect of heat treatment on Ni–B–Ce electroless coatings

“…Electroless plating technology, which shows great important application value, has become an environmentally friendly surface treatment process in many fields due to low cost and small environmental pollution. Previous studies usually studied the effect of heat treatment or ultrasound on Ni-P or Ni-B coatings and rarely combined these two factors with electroless deposition [16][17][18][19][20]. And few people have focused on the effect of heat treatment on ultrasonic-assisted electroless Ni-B-Ce coatings.…”

Enhanced mechanical properties and corrosion resistance of electro-deposited NiCoP composite coatings with ZrB2 particle addition

“…Alloying with cobalt can decrease both the E corr and i corr for all the coatings. The improvement of their corrosion resistance in NiCoP coatings could be attributed to the formation of a compact passive film of Ni 3 (PO 4 ) 2 in the corrosive environment [65]. In addition, nickel and cobalt elements can both form oxide layers (nickel oxide and cobalt oxide) on the sample surface when exposed to the air, which could effectively hinder corrosion in artificial seawater [66].…”

Recent advances in electroless-plated Ni-P and its composites for erosion and corrosion applications: a review

“…TiN nanoparticles are successfully incorporated into the electroless Ni-Co-P coating matrix to form a Ni-Co-P/ TiN nanocomposite on the Al substrate. Different weight percentages of cobalt were added to the aforementioned nanocomposite coating [70]. Microhardness levels were in turn enhanced as cobalt content levels in the nanocomposite increased, Fig.…”